The Coastal Salinity Index (CSI) utilizes salinity data to characterize saline (drought) and freshwater (wet) conditions in coastal areas. The CSI is site-specific and can be computed for multiple time intervals from 1- to 24-months, to help users evaluate response to monthly (and longer) precipitation and streamflow conditions. The Coastal Salinity Index (CSI) was developed to characterize coastal drought, monitor changing salinity conditions, and improve understanding of the effects of changing salinities on fresh and saltwater ecosystems, fish habitat, and freshwater availability for municipal and industrial use.

    Click on the station icon to access the following information:
  • The station identification number, station name and a link to the National Water Information System (NWIS) station current conditions page data.
  • The current CSI 12-month interval value.
  • The CSI stacked graph that allows the user to evaluate short (1-month) to long- (24-month) conditions in one graph. Go to the About the CSI tab to learn how to read and interpret the CSI stacked graph.
  • A link to all the CSI graphs for that particular gage.

Explanation for stacked graph.

Coastal Salinity Index

(12-month interval CSI values, as of )

  • CD4 or less
  • CD3 to
  • CD2 to
  • CD1 to
  • CD0 to
  • Normal to
  • None Not Available

  • Coastal Drought (CD)
  • Coastal Wet (CW)
  • CW0 to
  • CW1 to
  • CW2 to
  • CW3 to
  • CW4 or more
South Atlantic CSI Gages

Input Salinity Data (one file for all gages)
Hover mouse over Station Number to identify icon on the map

Station NumberStation Name Output CSI Data
0208114150ROANOKE RIVER AT NC 45 NR WESTOVER, NC 0208114150.csv
02081094ROANOKE RIVER AT JAMESVILLE, NC 02081094.csv
02110777AIW AT HIGHWAY 9 AT NIXONS CROSSROADS, SC 02110777.csv
02110770AIW AT GRAND STRAND AIRPORT N. MYRTLE BEACH, SC 02110770.csv
02110755AIW AT BRIARCLIFFE ACRES AT N. MYRTLE BEACH, SC 02110755.csv
02110760AIW @ MYRTLEWOOD GOLF COURSE @ MYRTLE BEACH, SC 02110760.csv
02110815WACCAMAW R NR HAGLEY LAND. NR PAWLEYS ISLAND, SC 02110815.csv
02172020W BRANCH COOPER R @ PIMLICO NR MONCKS CORNER, SC 02172020.csv
02172040BACK RIVER AT DUPONT INTAKE NR KITTREDGE, SC 02172040.csv
02172050COOPER R NR GOOSE CREEK, SC 02172050.csv
021720677COOPER RIVER @ FILBIN CREEK @ NORTH CHARLESTON, SC 0217205677.csv
021720698WANDO RIVER ABOVE MT PLEASANT, SC 021720698.csv
021720709COOPER RIVER AT U.S. HWY 17 AT CHARLESTON, SC 021720709.csv
021720710COOPER RVR @ CUSTOMS HOUSE (AUX) @ CHARLESTON, SC 021720710.csv
021989784L BACK RIVER ABOVE LUCKNOW CANAL, NR LIMEHOUSE, SC 021989784.csv
021989791LITTLE BACK RIVER AT F&W DOCK, NEAR LIMEHOUSE, SC 021989791.csv
02198920SAVANNAH RIVER AT GA 25, AT PORT WENTWORTH, GA 02198920.csv

The CSI is a standardized probability index. A value of zero indicates historical mean salinity amount, and positive and negative values represent increasingly fresh and saline conditions, respectively. The CSI uses the same classification scheme as the U.S. Drought Monitor for high saline, or drought, conditions (see table 1 on About the CSI tab).

The map on this page shows real-time CSI calculations (12-month interval) for 17 USGS-operated stations in North Carolina, South Carolina, and Georgia. The data used on this site come from the USGS NWIS database. All real-time data are provisional and subject to revision.

Salinity index values are calculated at the end of the day; the displayed values on the map are for the previous day ().

For more information about the development of this index, see About the CSI.

Coastal Salinity Index (CSI) Information
Coastal Salinity Classification Description Threshold Values Icon Cumulative Percentage
CD4 Exceptional salinity conditions -2.00 or less 2
CD3 Extreme salinity conditions -1.99 to -1.60 5
CD2 Severe salinity conditions -1.59 to -1.30 10
CD1 Moderate salinity conditions -1.29 to -0.80 20
CD0 Abnormal salinity conditions -0.79 to -0.50 30
Normal Normal salinity conditions -0.49 to 0.50 70
CW0 Abnormal freshwater conditions 0.51 to 0.80 80
CW1 Moderate freshwater conditions 0.81 to 1.30 90
CW2 Severe freshwater conditions 1.31 to 1.60 95
CW3 Extreme freshwater conditions 1.61 to 2.00 98
CW4 Exceptional freshwater conditions 2.01 or more 100
Not Available Missing Data

Questions or problems with the web pages? Contact rsyoung@usgs.gov.
Questions concerning CSI? Contact mdpetkew@usgs.gov.